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European astronomers have discovered a planet with the mass of Earth in the Alpha Centauri star system - the nearest star system to Earth.

Located less than 5 light-years away, the star system Alpha Centauri is the Earth's nearest neighbor. The system consists of 3 stars - two of which are similar to our own. And orbiting one of those stars, announced a team of astronomers, is a planet about the same mass as the Earth. Unfortunately, it's too close to the star to support life.

"This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it," stated team member Stéphane Udry in a press release, "But it may well be just one planet in a system of several."

That's a good hope to hold on to. After all, in our own solar system, the planet Venus is close to the size of Earth but incapable of supporting life. So it's possible that there may be more Earth-sized planets further out from the Sun.

The planet was detected using the High Accuracy Radial Velocity Planet Searcher (HARPS). Using HARPS, the team of astronomers detected the gravitational pull of the planet as it effected its star. This is the most precise type of measurement found with the instrument to date. But this is the team that knows how to do it - back in 1995, they discovered the first Earth-sized planet located outside of our solar system.

"Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days," said team leader Xavier Dumusque in the release.

This finding represents another milestone. Not only is the planet relatively close to Earth, it's also the first Earth-sized planet located around a Sun-like star. Other Earth-sized planets circle red dwarfs, and there's some debate among astronomers as to whether such planets could be inhabited by humans. Planets near Sun-like stars are much more likely to be able to support Earth-like life.

"This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun," added Xavier Dumusque. "We live in exciting times!"